void Sphere(GeometricObject obj)
{
var fcl = new Color(0.5f, 0.5f, 0.5f, 1.0f);
var stacks = 20;
var slices = 2 * stacks;
var radius = 1.0f;
obj.Begin();
obj.SetSphereStacks(stacks);
obj.SetSphereSlices(slices);
obj.SetSphereRadius(radius);
obj.SetSphereFrontColor(fcl);
obj.AddSphere(Vector3.zero);
obj.End();
}